SOCIAL AND POLITICAL ECONOMY. 189 



tendency on the part of many plants to store up 

 underground supplies, and has intensified it, and 

 so rendered the results more satisfactory ; just as 

 horticulturists have availed themselves of wild fruits, 

 and evolved our larger and more succulent kinds 

 from them. Our Carrots, Turnips, Mangel, Beet, etc., 

 are all artificial enlargements, for purposes of our 

 own, of the parts of plants which store up nutri- 

 tious food underground because of the rigour of 

 our northern winters. 



Not a few plants bury their stems underneath 

 the ground, in which case we know them as rhizomes. 

 The Bracken {Pteris aqinlina) always adopts this 

 plan, although its near relations, the Tree-ferns, lift 

 their fronds high up in the atmosphere by means of 

 thick trunks, which are the exact equivalents of the 

 underground creeping rhizome of the former. But 

 then the Bracken lives where there are cold winters, 

 and the Tree-ferns abound where the winters are 

 very mild. Our Sedges, Iris, and several others, have 

 adopted the same plan as the Bracken, and run 

 their stems beneath the soil, storing and saving up 

 in it all they have been able to accumulate over and 

 above what was necessary to carry on the general 

 expenses. Two very different kinds of organs 

 have thus been specialised to do the same kind of 

 work and to subserve the same economical end, as 

 shown by the rhizome of Solomon's Seal {Conval- 

 laria vtajaiis), whose popular name is derived from 



